Photonics Dictionary: A

An achromat, in the context of optics, refers to a type of lens or lens system designed to reduce chromatic aberration. Chromatic aberration is an optical phenomenon where different colors of light...

Technology that corrects the shape of reflective optics; primarily applied in large telescope systems, in order to compensate for slowly varying changes in temperature, wind and mechanical stress.

Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of atmospheric distortions. The Earth's atmosphere can cause light passing through it...

Also known as roof prism. A type of prism designed by G.B. Amici. It consists of a roof edge produced upon the long reflecting face of a right-angle prism. Used as an erecting system in elbow and...

An antireflection coating (AR coating) is a thin film or coating applied to optical surfaces, such as lenses or windows, to minimize unwanted reflections and increase the transmission of light...

An aplanatic surface is an optical surface that is specifically designed or shaped to minimize spherical aberration and coma. Spherical aberration is an optical aberration that occurs when light rays...

An aspheric lens is a type of lens whose surface profiles deviate from the traditional spherical shape. Unlike spherical lenses, which have a constant curvature across their surfaces, aspheric lenses...

An aspheric mirror is an optical mirror surface that deviates from the shape of a perfect sphere, having a non-spherical surface profile. Unlike traditional spherical mirrors, which have a curved...

A CCD sensor that provides feedback to the motion control system for a telescope, allowing the telescope to follow a particular object or section of sky automatically.

A low-power telescope placed at the eyepiece of an optical system to increase overall magnification. Most often used to evaluate image quality.